1. Field of the Invention
The present invention relates to a cushioning material provided between an inner housing and an outer housing and to an information storage device formed to have the cushioning material.
2. Description of Related Art
Hard disk drives (HDDs) play an important role as a recording/reproducing device for writing data or programs and reading recorded data and or the like in an information processing apparatus such as a personal computer.
The HDD is not only used as a main body of the information processing apparatus but also considered as a small information storage device (DHD) which is an external or so-called detachable extension device removably mounted on the main body of the information processing apparatus. Such an information recording device is removed from the main body of the information processing apparatus as required, and the removed device may be carried by itself or kept separately from the main body of the information processing apparatus. In addition, the device may be mounted on a portable apparatus for use.
When the HDD is mounted on an information processing apparatus, for example, some problems may occur in that the HDD requires a long time period for read or write operation due to effect of vibration or shock on the HDD through the information processing apparatus, or the information recording device may be dropped inadvertently while the device is carried as described above to cause the HDD to be broken due to the shock at the time of the drop.
The above-mentioned external information recording device typically has an HDD accommodated in a housing (for example, see Patent Document 1).
It is contemplated that the information recording device is configured to have a cushioning material made of sponge or the like in the housing for the purpose of protecting the HDD from the above-mentioned shock or vibration. However, such a cushioning material cannot be disposed in a low strength portion of the HDD such as a wiring board portion and the center of a top cover portion, which means that the cushioning material is provided partially for the housing. Thus, the cushioning material made of sponge or the like cannot achieve sufficient effect of shock absorption.
To avoid this, it is conceivable to use a cushioning material made of an elastic body such as rubber and gel or a viscoelastic body with higher elasticity than sponge. FIG. 27 shows a perspective view of an example of such a cushioning material.
This cushioning material 200 has a space 201 formed therein to come in contact with the housing for covering at least part of an inner housing. The cushioning material 200 has, as outer surfaces, a top surface 202A and a bottom surface 202B, and side surfaces 202C and 202D in two directions (an X direction and a Y direction) which are formed as contact surfaces to come in contact with inner surfaces of an outer housing.
The cushioning material 200 formed as above can convert shock energy from the outside into thermal energy through transformation to absorb the shock.
FIG. 28 shows an exemplary arrangement of the cushioning material 200 within housings. In this case, cushioning materials are provided at corners between an inside housing (an inner housing) and an outside housing (an outer housing). According no cushioning materials are provided in a low strength portion of an HDD such as a wiring board portion and the center of a top cover portion, it is expected that the effect of protecting the HDD to absorb shock is achieved.
[Patent Document 1]
Japanese Patent Publication No. 6-66111
The cushioning material is subject to significant deformation. Especially when an item to be protected by the cushioning material (a target item to be protected) receives a shock, the cushioning material is deformed in nature to the extent that it does not hold its original shape at all for an instant if no physical limitations are imposed on the cushioning material. This nature is seen with varying degrees when sponge is used and rubber or gel is used as the cushioning material.
In actual design, however, physical limitations are imposed which may prevent the cushioning material from being deformed sufficiently even when the cushioning material is provided. The cushioning material 200 shown in FIG. 27 has the cushioning effect as a material characteristic. However, when the cushioning materials 200 are disposed, for example as shown in FIG. 28, the cushioning materials 200 are surrounded by the inner housing and the outer housing and have no room for deformation. This makes it impossible to sufficiently deform the cushioning materials 200 when it receives a shock. Since the deformation of the cushioning materials is not promoted, the cushioning materials become harder when it receives a shock from the outside, and shock acceleration to the item to be protected by the cushioning material is not greatly reduced. As a result, the effect of shock absorption cannot be exerted sufficiently.
As described above, it is difficult for the conventional configuration to provide sufficient shock resistance of the HDD.